Edit: meant to put 3-4 minutes not 3/4
In: Engineering
Car heaters work by redirecting some of the engine coolant/antifreeze liquid away from the front radiator.
This doesn’t work however until the engine block itself warms up, which usually takes several minutes depending on the ambient temperature outside. Until that time, the circulating coolant will be no warmer than the engine block is.
Ypu can remedy this in two ways, the first is to throw away and organize the stuff in your garage and actually park your car in there if you own one. The second way is to buy an electric block heater for your car which plugs into one of your exterior outlets. This keeps the engine block generally above 0°C and reduces the amount of time needed to warm up in the morning.
Ocassionally some car makers have used electric heating elements to provide rapid heating. But this would actually consume a lot of electricity, which might drain the battery and would require a larger alternator to run which would soak power from the engine in a noticable way. Many modern cars have heated seats available as a purchase option. Unlike attempting to to heat all the air flowing continuously through the AC system, running a seat heater doesn’t consume that much electricity so this generally doesn’t necessitate major changes to the car electrical system.
In some of the newest cars the AC is designed so it can run in a *Heat Pump* mode. Essentially the AC configures itself to run in reverse using a pair of pressure regulating valves and a crossover valve to reverse the flow direction. Instead of pumping heat out of the air in the car’s cabin and then radiating it out from the condensor behind the front grille, it draws heat from the outside air, cooling down the condensor pack, then pumps the acquired heat into the AC core, heating the evaporator pack. This requites adjusting the pressure of the refrigerant on each side which is done by a computerized control system.
It turns out that this scheme is much more efficient than using an electrically heated coil. (Although it is much more complex from an engineering standpoint.) AC units have a Coefficient of Performance (C.p.) of about 3x-5x, meaning that for every kilowatt of electricity they consume or mechanical power from the car’s serpentine belt, they can move 4kw-5kw of heat.
Just like an electric soace heater in your house, this would only take a few tens of seconds to start noticeably warming the air.
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